In the now 50-year war that the U.S. has waged against poverty (mark your calendars to celebrate on Jan. 8, folks), one of the most tightly contested battlegrounds has been single moms. How do we get them — and ergo their children — out of poverty? A new report suggests that one approach, getting mothers married, is not useful and may in fact make things worse.

The issue is significant: more than 40% of all births in the U.S. are now to unwed moms. It’s becoming as common a way of starting a family as getting married first. And yet, according the U.S. Census Bureau, about 46% of children in single-mother households were living in poverty in 2013. Only 11% of kids living with two married parents were.

It would seem to make sense that a two-parent household was better able to handle the expense, time and energy that raising children requires. Thus, some states have allocated some of their funds earmarked for the needy to have marriage education, to try to cut off poverty at the aisle, so to speak.

But some experts criticize that as a waste of money. At heart, the question policymakers disagree on is this: Are single mothers poor because they’re single, or are they single because they’re poor?

Kristi Williams, an associate professor in sociology at Ohio State University, has written a paper on the issue for the Council on Contemporary Families, and her conclusions are that it’s the latter and that marriage won’t solve anything. “The biological fathers of the children of low-income single mothers have high rates of poverty, incarceration, and are likely to have children from other relationships,” she says.

Poverty, with its dreary companions — unemployment, lousy health, rotten housing, hunger and hopelessness, to name a few — puts a lot of pressure on a relationship. Not many couples make it. Marrying a guy who’s not the father of the kids is very difficult—and can be dangerous for the kids. “Marriages to the biological father also have high rates of divorce,” says Williams. “And research suggests that marrying and then divorcing is associated with worse economic and health outcomes among single mothers than remaining single.”

Williams’ paper acknowledges that when two very poor biological parents of children marry and stay together, it does lead to better outcomes for the children, but it says that this is extremely rare. “A nationally representative study of more than 7,000 women found that approximately 64% of the single mothers who married were divorced by the time they reached age 35-44,” she writes. Other studies have suggested that when single mothers exit poverty, it’s usually not because of changes in family composition.

She also takes issue with one current nonmarital approach to the issue: encouraging poor women to delay having kids. For some women, especially African Americans, this is a nonstarter, Williams writes. “Later ages at birth are associated with higher rates of neonatal mortality, perhaps because the stress of chronic disadvantage and racial discrimination accelerates biological aging for this group.”

Her suggestion instead is to focus on unintended or mistimed births. According to Williams’ research, if the women anticipated having a baby without having a husband, then their mental health didn’t take such a pummeling from motherhood. These are the so-called single mothers by choice. “Those who anticipated the nonmarital birth had no worse mental health later in life than those whose first birth was marital — while those who had not anticipated it did have worse mental health,” she writes. In practice, Williams’ approach would mean more sex ed and more and cheaper access to birth control.

Not everybody agrees that we should give up on marriage. “Virtually no poor, single mother wishes for her daughter or son to recapitulate her family experience,” says Bradford Wilcox, director of the National Marriage Project and associate professor of sociology at the University of Virginia. “Marriage as the anchor for family life is a nearly universal dream in America, regardless of income.” As evidence, he points to the work of sociologists like Andrew Cherlin, author of The Marriage-Go-Round, who says that marriage is still a cherished cultural institution. (Although he also notes that Americans like to divorce a lot, too.)

But Wilcox and Williams seem to agree on one thing: marriage ain’t what it used to be as a building block for society. “Marriage is not some kind of magic fairy dust that you just sprinkle on a relationship in the hopes that it will be stable and happy,” says Wilcox. “Marriage as an institution is most likely to flourish when it is embedded in a society or in communities that lend legal, cultural and economic support to the ideals of permanency, fidelity, mutual aid and shared childrearing associated with marriage.” Since support for those ideals has been dwindling across the socioeconomic spectrum, but especially among poorer communities, “it is not surprising that marriage is not delivering as much stability and support as it once did to poor couples.”